1. Field of the Invention
The present invention relates to a camera and a lens driving method, wherein stepping motor drives a zoom lens and a focus lens.
2. Description of the Related Art
In an electronic camera such as a digital still camera, a zoom tracking operation has to be performed wherein a focus lens is moved in accordance with the movement of a zoom lens. By this operation, the zoom lens and the focus lens are kept driven in accordance with the zoom operation, so that an object to be photographed can be in focus even when the angle of view (i.e., the magnification) of the camera is changed.
In the zoom tracking operation, the focus lens has to be moved to the focus position corresponding to the zoom position so that the same object can be kept in focus before and after the zoom operation. In order to maintain the in-focus state of the focus lens during the zoom operation, the zoom tracking operation has to be performed in such a manner that the position of the focus lens and the position of the zoom lens has such relationships as shown in FIG. 2, for example.
In a conventional lens control device for driving two lenses, the speed at which the magnifying lens is moved is smoothly controlled for maintaining the in-focus state. An example of such a conventional lens control device is disclosed in Jpn. Pat. Appln. KOKAI Publication No. 6-62300, for example.
In the lens control device described in Jpn. Pat. Appln. KOKAI Publication No. 6-62300, the microcomputer for lens control can control the stepping motor (zoom motor) in such a manner as to change the moving speed of the magnifying lens, if the moving speed of the focus compensation lens exceeds a preset value when the magnifying lens is moving.